Method for preparing 4-substituted-1 2 4-triazoles

ABSTRACT

A METHOD FOR PREPARING A 4-SUBSTITUTED-1,2,4-TRIAZOLE WHICH COMPRISES REACTING AN N-ALKOXYMETHYLENE-N&#39;&#39;-FORMYLHYDRAZINE WITH A PRIMARY AMINE.

United States Patent ()fice Patented Mar. 7, 1972 US. Cl. 260-308 R 4 Claims ABSTRACT or THE DISCLOSURE A method for preparing a 4-substituted-1,2,4-triazole which comprises reacting an N-alkoxymethylene-N-formylhydrazine with a primary amine.

This invention is concerned with a novel method for preparing 4-substituted-1,2,4-triazoles of the formula wherein R is selected from the group consisting of alkyl, straight or branched, of 1 to 18 carbon atoms which may be substituted with one or more halo preferably chloro, lower alkoxy, hydroxy, phenyl, nitro, lower-alkylamine or di(1ower-alkyl)amino groups, a COY group wherein Y stands for OH, lower alkyl, lower alkoyl or the -NR R group wherein R and R are hydrogen or lower alkyl, and a phenoxy or thiophenoxy group which may be substituted in the aryl group with lower alkyl, lower alkoxy, halo preferably chloro, or nitro groups; alkenyl of 2 to 6 carbon atoms; alkynyl of 2 to 6 carbon atoms; cycloalkyl of 3 to 8 carbon atoms; aralkyl of up to carbon atoms; aralkyl of up to 10 carbon atoms substituted in the aryl group with lower alkyl, lower alkoxy, halo preferably chloro, and nitro groups; aryl; lower alkyl, lower alkoxy, halo preferably chloro and nitro substituted aryl; and heterocyclic groups, preferably selected from the group consisting of 2-pyridyl, 3-pyridyl, 4-pyridy1, 3-(1, 2,4-triazyl), 4-(l,2,4-triazyl), 2-pyrimidy1, Z-thiazyl, 2- benzotln'azyl and its chlorinated derivatives. The term lower as used above refers to a carbon content of l to 6 carbon atoms. 7 g V The 4-substituted-1,2,4-triazoles are useful as fungicides, particularly'for the control of rusts on cereals, and as intermediates for the preparation of pesticidal compounds.

The synthesis of 4-substituted-1,2,4-triazoles has been reviewed by K. T. Potts, Chemical Reviews 61, 95-6 (1961). As stated therein the method of choice for the preparation of the compounds of this invention has been the reaction of an aliphatic, aromatic or heterocyclic primary amine (RTNH with diformylhydrazine. The following reaction depicts this.

NHCHO V NHCHO Bartlett and Humphrey, J. Chem. Soc. 1967, 1664, is by 2 the transamination of N,-N-dimethyl:formamide azine with primary amines. c

The following reaction depicts this L J 2 lie lll-i This method requires isolation of the intermediate azine.

The novel method of preparation of this invention consists in the reaction of an orthoformate, (RO) H, with formylhydrazine to give an N-alkoxymethylene-N'-formylhydrazine which is then reacted with a primary amine, RNH wherein R has the meaning given above. The following reaction depicts this:

(R'O) CH NHQNHCHO ROOH=NNHCHO RNH The orthoformates used are those where R is alkyl and preferably where R is lower alkyl of 1 to 6 carbon atoms. Typical of these is where R is methyl, ethyl or isopropyl. Orthoformates are well-known compounds and are products of commerce.

Formyl hydrazine is a product of commerce.

N-ethoxymethylene-N'-formylhydrazine is typical of the compounds of Formula II and is known from the work of Ainsworth and Hackler, J. Org. Chem. 31, 3442-4 '(1966). The intermediate N-alkoxymethylene-N-formylhydrazine may be isolated, or may be used directly without isolation, for the subsequent reaction with the primary amine.

For the reaction of the orthoformate with formylhydrazine, equimolar quantities of the reactants may be used or else an excess of the orthoformate up to molar excess may be used. An acid catalyst, such a formic acid, may sometimes facilitate the reaction of the orthoformate with formylhydrazine.

For the reaction of an N-alkoxymethylene-N-formy1 hydrazine with the primary amine, equimolar quantities are usually used although up to 100% molar excess of the amine may be used.

Although the series of reactions will proceed without the use of a solvent, a solvent is preferred. The preferred solvent is an anhydrous alcohol, such as anhydrous methanol, ethanol or isopropanol. A small amount of water may be tolerated, but even with 95% ethanol considerable by-products, notably 4-formylamino-l,2,4-triazole, are obtained.

The series of reactions will proceed at room temperature and in the range of 0 to 150 C. Reflux temperatures in the range of 50 to-l00 C. are preferred.

'The resulting 4-substituted-1,2,4-triazoles may be isolated as the crude product or may be purified by standard means, such as distillation or recrystallization. Structures may be confirmed by spectral data such as nmr.

The following examples are offered to illustrate the method of preparation of this invention and are not to be construed as limitations thereof.

EXAMPLE 1 Preparation of 4-butyl-l,2,4-triazole A 2-liter flask was chargedwith 440 g. (3 moles) of triethyl orthoformate, g. (2 moles) of formylhydra- Zinc and 800 ml. of anhydrous methanol. The reaction mixture was stirred at reflux temperature (65-70 C.) for 3.5 hrs. The progress of the reaction was followed hourly I 4 EXAMPLE 4 Preparation of 4-(2-pyridyl)e1,2,4-triazole A reaction mixture consisting of g. (0.086 mole) of N-ethoxymethylene-N'-formylhydrazine, 8.1 g- 10.086 mole) of 2 aminopyridine and 200 cc. of absolute ethanol --147 C., which was Analytical data, percent C. and 145 g. (2 moles) of nbutylamine was added in minutes. A slight exotherm was heated at reflux for 16 hrs. The solvent was stripped off. The resulting residue was recrystallized from benzene to give 7.4 g. of solid melting at 145 C 4-(2-pyridyl)-1,2,4-triazole. EXAMPLE 5 Amazole Preparation of 4-[fl-(ZA-dichlorophenoxy) ethyl]-l,2,4-triazole A reaction mixture consisting of 10 g. (0.086 mole) of N-ethoxymethylene-N'-formylhydrazine, 17.7 g. (0.086 mole) of ,8-(2,4-dichlorophenoxy)ethylamine and 100 cc. EXAMPLE 2 of absolute ethanol was heated at reflux for 16 hrs. The solvent was then stripped oif leaving a solid. The solid was recrystallized from acetone/hexane to give 7 g. melting at 115 -117 C. This was found to contain by analysis 46.6% C, 3.7% H, 27.2% Cl, 16.3% N and 6.8% 0; calculated for C H Cl N 0 is 46.5% C, 3.5% H, 27.5% CI, 16.3% N and 6.2% O. The product is 4-[;8-(2,4-dichlor0phenoxy)ethyl]-1,2,4-triazole.

EXAMPLE 6 Preparation of 4-[fi-(4-chlorothiophenoxy) ethyl]-l,2,4-triazole A reaction mixture consisting of 5.75 g. (0.0495 mole) of N-ethoxymethylene-N'-formylhydrazine 9.3 g. (0.0495 mole) of B-(4-chlorothiophenoxy)ethylamine and 100 cc. EXAMPLE 3 of absolute ethanol was heated at reflux for 16 hrs. The Preparation of 4-phenyl-l,2,4-triazole solvent was stripped oif leaving a solid residue. The product was recrystallized from acetone/hexane to give 6 g. of solid melting at 7375 C. This was found to contain by (0.086 analysis 49.9% C, 4.2% H, 14.7% C1, 17.6% N and mole) of aniline and 200 cc. of absolute ethanol was 13.2% S; calculated for C H C1N SlS 50.3% C, 4.2% H, 14.65% Cl, 17.6% N and 13.4% S. The product is 4-[B-(4-chlorothiophenoxy)ethyl-1,2,4-triazole. I

The following Table I lists typical 4-substituted-1,2,4- triazoles which may be prepared by this novel method.

TABLE I 4-substltutod-1,2,4-trlazoles of the formula Melting C.) or Empirical R boiling point- OJmm.) formula by means of gas-liquid chromatography. The reaction mixture was cooled to raised the temperature about 5 C. The reaction mixture was stirredat reflux temperature for 3 hrs. and was then stripped of solvent and excess'triethyl orthoformate by heating on a steam bath at reduced pressure, down to 20 mm. There was obtained a yellow oil residue of 250 g. which by elution gas-liquid chromatography was shown to be at least of 4-butyl-1,2,4-triazole. A further 10 stripping of this residue at a pot temperatureof 190 and 10 mm. pressure gave 216 g. of light amber oil residue which was an 86% yield of crude 4-butyl-l,2 shown to be 93% pure by gas-liquid chromatography. The product was further purified by distillation. The main frac- 15 tion distilled at C. at 2 mm. pressure and was a 77% weight yield of 4-n-butyl-l,2,4-triazole melting at 50 C.

Preparation of 4-isoamyl-1,2,4-triazole A reaction mixture consisting of 10 g. (0.086 mole) of N-ethoxymethylene-N'-formylhydrazine, 7.5 g. (0.086 mole) of isoamylamine and 200 cc. of absolute ethanol was heated at reflux for 16 hrs. The ethanol was removed by heating under vacuum and the residue distilled. A main fraction distilled at 153-163 C./0.2 mm. and amounted to 5.4 g. This was found to contain by analysis 60.5% C, 9.7% H, and 30.4% N; calculated for C H N 30 is 60.4% C, 9.4% H, and 30.2% N. The product is 4- isoamyl-l,2,4-triazole.

A reaction mixture consisting of 10 g. (0.086 mole) of N-ethoxymethylene-N'-formylhydrazine, 8.0 g.

heated at reflux for 16 hrs. The resulting product was 40 stripped of solvent leaving solid residue. The residue was recrystallized from benzene to 4.6 g. of solid melting at 101-102 C., which was 4-pheny1-1,2,4-triazole.

Prop.

&7 33 3 0 0 7 0 7 ow1 3 9 9 7 3 2 9)) 8 06 2 1 eh h c .s .8716 68 .999899 4 677888m6 .m 23 3 hem h wmcoowoobwwwwnnmmnwmnoc mm Analytical data, percent TABLE I-Continued Melting C.) or Empirical boiling point CJmm.) formula 101-103 CmHuNaO Prep.

2 9 7 aateae S new. a NNN 4460566. ahll mmnmnnnnnfimm CCOCCCCCCCCCC References Cited Ainsworth et al.: J. Org. Chem., vol. 31, pp. 3442- 44 (1966).

U5. (:1. X.R. 45 260-256.4 N, 296 R, 305, 306.8 R; 424-251, 263, 269,

ROCH=NNHCHO wherein R is an alkyl group, with a primary amine of the formula RNH wherein R has the meaning given above.

C. was found by analysis to contain 51.2% C, 5.5% H, 19.1% Cl, 7.32% S is 51.1% 8.9% 01, 7.5% N and 17.1% s. CH OCsHiSCHzCHzNHz distilled at mm. and was found by analysis to contain 57.7% C, 6

. H, 7.7% N, 8.7% o and 17.5% s.

. and was found by analysis to contain 43.0% C, 4.6% H, 32.0% C1, .0% H, 32.0% G1, 6.3% N and 14.4% s.

benzothiazyl which comprises reacting an N-alkoxymethyl- 25 ene-N'-formyhydrazine of the formula 2. A method according to claim 1 wherein R is an alkyl group.

.3. A method according to claim 1 wherein R is a butyl group. 4. A method according to claim 1 wherein R' is an alkyl group of 1 to 6 carbon atoms.

henyl, a dia COY group wherein Y stands 40 which may be sub- 34 kynyl of ALTON D ROLLINS Primar Exam'n 2 to 6 carbon atoms; cycloalkyl of 3 to 8 carbon atoms; y 1 er a Figures in parentheses are those calculated from the empirical formula. 1 b lThe intermediate A1'yl-SCH2C HzNHz was made by reaction of Z-chloroethylamine hydrochloride with the appropriate sodium t iiop ienate.

4-ClO H4SOH OHzNHz distilled at 97100 N 16.2% S; calculated for cgHmclN 11.0% 0 and 17.3% S; calculated for OQHHNOS 3,4-C12CuH SCH2CHzNH2 distilled at -1 6.2% N and 14.3% S; calculated for O HnClzNs is I claim: 1. A method for preparing a compound of the formula ht or branched, of l to 12 carbon atoms which may with lower alkoxy, or chloro and heterocyclic groups selected from the l, 3-py-ridyl, 4-pyridyl, 3-(1,2,4-

wherein R is selected from the group consisting of alkyl, straig be substituted with lower alkoxy, hydroxy, p (lower-alkyl) amino group,

for lower alkyl, and a phenoxy group stituted with lower alkoxy, or chloro groups; al

benzyl; benzyl substituted groups; phenyl class consisting of Z-pyridy triazyl), 4-(1,2,4-triazyl), 2-pyrimidy1, Z-thiazyl and 2- 

